[TxMt] Re: [FIXED] Interactive Input on Snow Leopard.

[Adam R. Maxwell]

On Sep 10, 2009, at 7:00 PM, Luke Daley wrote:

> On 10/09/2009, at 11:55 PM, Adam R. Maxwell wrote:
>
>> ISTR the crash I saw on Snow Leopard looked like it was calling
>> malloc (via strdup in mode.c) before the system's malloc zone was
>> set up.  Is that still the case?
>
> TBH, it was very difficult to determine exactly what was going on. I
> was operating under the assumption that the problem was due to
> something in our read() implementation calling something that in turn
> invoked read() causing a recursion. Your explanation makes more sense.
> I'll test this and let you know.

That was just my guess based on the stack trace I saw, and a glance at  
the code confirmed that mode_contains calls strdup.  If my guess is  
correct, that particular issue could likely worked around by using  
vm_allocate instead of strdup; I never got around to trying it myself,  
though.  I have yet to look at the Darwin source to see why Apple is  
calling arc4random when creating the scalable zone now...

>> Also, for my own curiosity, is it a problem that your read override
>> doesn't appear to be async-signal safe?
>
> Absolutely no idea.
>
> How would I make it async-signal safe

Well, my understanding is that you'd be limited to functions listed in  
the man page for sigaction(2).  So strdup/getenv/etc would be off  
limits.  Not much fun.

> and why would I do this?

My guess is that it would matter if code using the library relies on  
calling read() from a signal handler.  Signal handling is outside my  
area of expertise, so I was hoping someone else would have an answer :).


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